1. Technical Field of the Invention
The present invention relates to a method and apparatus for estimating behaviors of a vehicle, such as a direction of a vehicle or an area occupied by the vehicle on the local coordinate system, by using GPS (Global Positioning System) signals. In the present invention, the local coordinate system includes the LLS (local-level system), ENU (east-north-up), and Universal Transverse Mercator.
2. Related Art
A technique is known in which a GPS (global positioning system) antenna is provided on a vehicle to receive the GPS signals transmitted from a satellite, and vehicle conditions are estimated based on the received GPS signals.
Japanese Patent Laid-Open Publication No. 2005-186739, for example, discloses a technique for estimating traveling speed of a vehicle based on an actual location of the vehicle, which is specified by the GPS signals, and for determining the vehicle conditions (primarily, tire pressure) based on the traveling speed.
In the conventional art, the actual location determined based on the GPS signals have merely been indicated as a point. This has only enabled estimation on the actual location or the traveling speed of a vehicle with the location of the GPS antenna as a reference. Thus, the conventional art has not come up to estimating vehicle behaviors, such as a direction of a vehicle or an area occupied by the vehicle on the local coordinate system.
Estimating vehicle behaviors, such as a direction of a vehicle or an area occupied by the vehicle on the local coordinate system is advantageous in controlling the vehicle well to achieve stability of traveling, for example.